Position detection apparatus having a plurality of detection sections, and exposure apparatus

ABSTRACT

A surface position detection apparatus of this invention includes a position detection section having a plurality of electrodes opposing the object surface to be measured, and a measurement device for selecting at least one electrode of the plurality of electrodes in accordance with the shape of the object surface, supplying an AC current to the selected electrode, and measuring the current flowing to the electrode, thereby measuring the distance between the electrode and object surface.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a position detection apparatusfor detecting the surface position of an object, an exposure apparatushaving the position detection apparatus, a control method therefor, anda device manufacturing method.

[0003] The position detection apparatus of the present invention can beapplied to, e.g., a surface position measuring apparatus for measuring asmall distance by an electrostatic scheme. The exposure apparatus of thepresent invention can be applied to, e.g., a slit-scan exposureapparatus.

[0004] 2. Description of the Related Art

[0005] As surface position detection apparatuses for semiconductorexposure apparatuses, position detection apparatuses which obliquelyirradiate a semiconductor wafer, placed at a position where a maskpattern is to be transferred through a projecting lens, with light froma projector, and detect light obliquely reflected by the surface of thesemiconductor wafer to detect the surface position are widely used. FIG.9 is a schematic view of such a conventional surface position detectionapparatus.

[0006] As shown in FIG. 9, illumination light emitted from the outputend of an optical fiber 9 illuminates a pattern forming plate 11 througha condenser lens 10. The illumination light passing through the patternforming plate 11 is projected onto the exposure surface of a wafer 5through a lens 12, mirror 13, and projection objective lens 14, so theimage of the pattern on the pattern forming plate 11 is formed on theexposure surface of the wafer 5 from an oblique direction with respectto an optical axis EX. The illumination light reflected by the wafer 5is reprojected onto the light-receiving surface of a light-receivingdevice 18 through a condenser objective lens 15, mirror 16, and imaginglens 17. The image of the pattern on the pattern forming plate 11 isformed on the light-receiving surface of the light-receiving device 18.When the wafer 5 moves in the vertical direction, the image of thepattern moves to the left or right on the light-receiving surface 18.When an arithmetic circuit 19 calculates the position of the pattern,the surface position of the wafer 5 can be detected.

[0007] In the exposure apparatus, such a focus detection system has aplurality of measurement points in one shot (area to be exposed) of awafer. A surface position Z and tilt component (tilt) of the measurementshot are calculated by comparing the measurement results at theplurality of measurement points within the X-Y plane. Highly accuratefocus position control is achieved by controlling a Z-tilt stage 8.

[0008] In recent years, a slit-scan exposure apparatus which exposeswhile holding a reticle and wafer conjugate with a projecting lens andscanning both the reticle and wafer to increase the exposure area hasreceived a great deal of attention. In this exposure apparatus, a focusdetection signal is directly used as a closed loop signal forcontrolling the posture of the stage. As the signal, a signal as smoothas possible, i.e., a signal averaged for an exposure area is necessary.

[0009] However, since the slit light projection scheme cannot measureposition while uniformly illuminating a measurement surface of interest,the measurement areas always become discrete. In addition, experimentsconducted by the present inventors have revealed that when a thinslit-like light beam irradiates the edge portion of a step, thereflected light is scattered to generate a large focus detection error.

[0010] This problem can be solved by using an electrostatic sensor as afocus detection sensor. An electrostatic sensor is more advantageous asa focus detection sensor of a slit-scan exposure apparatus than anoptical sensor because it can almost uniformly average within thedetection area, does not generate any focus detection error at an edgeportion, and has high response speed.

[0011]FIG. 10 is a view showing the principle of distance measurement byan electrostatic sensor. Referring to FIG. 10, a flat electrode 30 usedfor measurement is arranged near an object 31 to be measured. Ahigh-frequency voltage is applied from an oscillator OS to the flatelectrode 30. An ammeter AM is connected between the flat electrode 30and oscillator OS. The ammeter AM and a measurement device 32 connectedto the ammeter AM measure the magnitude of an AC current flowing to theflat electrode 30. The current measurement result is input to anarithmetic circuit 33. A distance d between the flat electrode 30 andthe object 31 to be measured is measured by arithmetic processing by thearithmetic circuit 33.

[0012] Although the above-described surface position detection apparatuscan obtain high accuracy in detecting the surface position of asubstrate having a chip layout (pattern of a chip) compatible with theapparatus, no high accuracy can be obtained in detecting the surfaceposition of a substrate having a chip layout incompatible with theapparatus.

[0013] In addition, when the shape of the wafer surface changes to ashape incompatible with to the apparatus because of the repeatedlithography process, the above-described surface position detectionapparatus cannot accurately detect the surface position of thesubstrate.

SUMMARY OF THE INVENTION

[0014] The present invention has been made in consideration of the abovesituation, and has as its object to accurately detect the surfaceposition of an object to be measured independently of the surface stateof the object.

[0015] According to the first aspect of the present invention, there isprovided a position detection apparatus for detecting a position of anobject surface in a direction normal thereto, comprising at least twodetection sections, a selection section for selecting at least onedetection section from the at least two detection sections, and ameasurement device for measuring the position of the object surface inthe direction normal thereto using the detection section selected by theselection section.

[0016] In the position detection apparatus according to the firstaspect, preferably, for example, each of the at least two detectionsections has an electrode, and the measurement device applies anelectrical signal containing an AC component to the electrode of theselected detection section to measure a distance between the electrodeand the object surface.

[0017] In the position detection apparatus according to the firstaspect, for example, the electrodes of the at least two detectionsections preferably oppose different portions of the object surface.

[0018] In the position detection apparatus according to the firstaspect, for example, the electrodes of the at least two detectionsections are preferably in one plane.

[0019] In the position detection apparatus according to the firstaspect, for example, the electrodes of the at least two detectionsections are preferably concentric with each other.

[0020] In the position detection apparatus according to the firstaspect, for example, the selection section preferably alternativelyselects one detection section from the at least two detection sections.

[0021] In the position detection apparatus according to the firstaspect, for example, the selection section preferably selects at leastone detection section such that the number of detection sections to beselected changes.

[0022] In the position detection apparatus according to the firstaspect, for example, the selection section preferably selects at leastone detection section in accordance with a shape of the object surface.

[0023] In the position detection apparatus according to the firstaspect, for example, preferably the apparatus comprises at least twosets of the at least two detection sections, the selection sections, andthe measurement devices, and further comprises an arithmetic section forcalculating a tilt of the object surface on the basis of a measurementresult by the at least two measurement devices.

[0024] According to the second aspect of the present invention, there isprovided an exposure apparatus having a projecting lens for projecting apattern onto a substrate, a stage which moves while supporting thesubstrate, a position detection section for detecting a position of asubstrate surface in a direction of an optical axis, and a controlsection for controlling the stage on the basis of an output from theposition detection section, the position detection section comprising atleast two detection sections, a selection section for selecting at leastone detection section from the at least two detection sections, and ameasurement device for measuring a position of the substrate in adirection normal thereto using the detection section selected by theselection section.

[0025] In the exposure apparatus according to the second aspect,preferably, for example, each of the at least two detection sections hasan electrode, and the measurement device applies an electrical signalcontaining an AC component to the electrode of the selected detectionsection to measure a distance between the electrode and the substratesurface.

[0026] In the exposure apparatus according to the second aspect, forexample, the electrodes of the at least two detection sectionspreferably oppose different portions of the substrate surface.

[0027] In the exposure apparatus according to the second aspect, forexample, the electrodes of the at least two detection sections arepreferably in one plane.

[0028] In the exposure apparatus according to the second aspect, forexample, the selection section alternatively selects one detectionsection from the at least two detection sections.

[0029] In the exposure apparatus according to the second aspect, forexample, the selection section preferably alternatively selects onedetection section from the at least two detection sections.

[0030] In the exposure apparatus according to the second aspect, forexample, the selection section preferably selects at least one detectionsection such that the number of detection sections to be selectedchanges.

[0031] In the exposure apparatus according to the second aspect, forexample, the selection section preferably selects at least one detectionsection in accordance with a shape of the substrate surface.

[0032] In the exposure apparatus according to the second aspect, forexample, the selection section preferably selects at least one detectionsection in accordance with a position of the stage or the substrate.

[0033] In the exposure apparatus according to the second aspect, forexample, the selection section preferably selects the detection sectionto be used for measurement not to measure the position of the substratein the direction normal thereto on a scribing line of the substrate.

[0034] In the exposure apparatus according to the second aspect, forexample, the selection section preferably determines the number ofdetection sections for measurement in accordance with the pattern formedon the substrate.

[0035] In the exposure apparatus according to the second aspect, forexample, the selection section preferably determines detection sectionsto be used for measurement to reflect, on the measurement result, aposition of an exposure area on the substrate in the direction normalthereto where high resolving performance is required.

[0036] In the exposure apparatus according to the second aspect, forexample, the selection section preferably determines the number ofdetection sections to be used for measurement to reflect, on themeasurement result, a position of an exposure area on the substrate inthe direction normal thereto where high resolving performance isrequired.

[0037] According to the third aspect of the present invention, there isprovided an exposure apparatus having a projecting lens for projecting apattern onto a substrate, a stage which moves while supporting thesubstrate, first and second position detection sections for detecting aposition of a substrate surface in a direction of an optical axis, and acontrol section for controlling a tilt of the stage on the basis ofoutputs from the first and second position detection sections, each ofthe first and second position detection sections comprising at least twodetection sections, a selection section for selecting at least onedetection section from the at least two detection sections, and ameasurement device for measuring a position of the substrate in adirection normal thereto using the detection section selected by theselection section.

[0038] In the exposure apparatus according to the third aspect,preferably, for example, each of the at least two detection sections hasan electrode, and the measurement device applies an electrical signalcontaining an AC component to the electrode of the selected detectionsection to measure a distance between the electrode and the substratesurface.

[0039] In the exposure apparatus according to the third aspect, forexample, the electrodes of the at least two detection sectionspreferably oppose different portions of the substrate surface.

[0040] In the exposure apparatus according to the third aspect, forexample, the electrodes of the at least two detection sections arepreferably in one plane.

[0041] In the exposure apparatus according to the third aspect, forexample, the electrodes of the at least two detection sections arepreferably concentric with each other.

[0042] In the exposure apparatus according to the third aspect, forexample, each of the selection section of the first position detectionsection and the selection section of the second position detectionsection preferably selects a detection section such that both thedetection section of the first position detection section and thedetection section of the second position detection section, which are tobe used for measurement, are positioned on an inner area of a width ofthe pattern projected by the projecting lens and a distance between thedetection sections is maximized. Preferably, the substrate is exposedwhile projecting slit-shaped light onto the substrate through theprojecting lens and moving the stage.

[0043] In the exposure apparatus according to the third aspect, forexample, each of the selection section of the first position detectionsection and the selection section of the second position detectionsection preferably selects a detection section such that both thedetection section of the first position detection section and thedetection section of the second position detection section, which are tobe used for measurement, are positioned inside a width of the patternprojected by the projecting lens on the substrate and a distance betweenthe detection sections is maximized. Preferably, the substrate isexposed while projecting slit-shaped light onto the substrate throughthe projecting lens and moving the stage.

[0044] According to the fourth aspect of the present invention, there isprovided a position detection method of detecting a position of anobject surface in a direction normal thereto, comprising the selectionstep of selecting at least one detection section from at least twodetection sections, and the measurement step of measuring the positionof the object surface in the direction normal thereto using the selecteddetection section.

[0045] According to the fifth aspect of the present invention, there isprovided a method of controlling an exposure apparatus having aprojecting lens for projecting a pattern onto a substrate, a stage whichmoves while supporting the substrate, a position detection section fordetecting a position of a substrate surface in a direction of an opticalaxis, and a control section for controlling the stage on the basis of anoutput from the position detection section, comprising the selectionstep of selecting at least one detection section from at least twodetection sections, and the measurement step of measuring a position ofthe substrate in a direction normal thereto using the selected detectionsection.

[0046] According to the sixth aspect of the present invention, there isprovided a method of controlling an exposure apparatus having aprojecting lens for projecting a pattern onto a substrate, a stage whichmoves while supporting the substrate, first and second positiondetection sections for detecting a position of a substrate surface in adirection of an optical axis, and a control section for controlling atilt of the stage, each of the first and second position detectionsections comprising at least two detection sections, comprising theselection step of selecting at least one detection section from the atleast two detection sections of the first position detection section andat least one detection section from the at least two detection sectionsof the second position detection section, and the measurement step ofmeasuring the tilt of the substrate using the selected detection sectionof the first position detection section and the selected detectionsection of the second position detection section.

[0047] According to the seventh aspect of the present invention, thereis provided a device manufacturing method comprising the steps ofplacing a substrate applied with a resist film on a stage of an exposureapparatus, selecting at least one detection section of at least twodetection sections for measuring a position of the substrate in adirection of an optical axis and measuring the position of the substrateon the stage in the direction of the optical axis using the selecteddetection section, controlling the stage in accordance with ameasurement result in the measurement step, forming a pattern on thesubstrate on the stage by exposure, and developing the substrate.

[0048] According to the eighth aspect of the present invention, there isprovided a device manufacturing method comprising the steps of placing asubstrate applied with a resist film on a stage of an exposureapparatus, selecting at least one detection section from each of twoposition detection sections each having at least two detection sectionsfor measuring a position of the substrate in a direction of an opticalaxis and measuring a tilt of the substrate on the stage using theselected detection sections, controlling the tilt of the stage inaccordance with a measurement result in the measurement step, forming apattern on the substrate on the stage by exposure, and developing thesubstrate.

[0049] According to the present invention, the height or tilt of anobject surface can be accurately measured independently of the surfaceshape of the object.

[0050] According to the ninth aspect of the present invention, there isprovided a surface position detection apparatus which uses anelectrostatic sensor having an electrode arranged on a surface to bemeasured, voltage application means for applying a high-frequencyvoltage between the electrode and the surface to be measured, anddetection means for detecting a distance between the surface to bemeasured and the electrode on the basis of a value of a current flowingwhen the high-frequency voltage is applied between the electrode and thesurface to be measured, the electrostatic sensor having a plurality ofelectrodes as the electrode, and selection means for selecting theelectrode to be used.

[0051] According to the 10th aspect of the present invention, there isprovided an exposure apparatus comprising the surface position detectionapparatus for detecting a position of a surface to be exposed, and meansfor controlling the selection means in correspondence with a state ofthe surface to be exposed, whose surface position is to be detected.

[0052] According to the 11th aspect of the present invention, there isprovided a device manufacturing method using the exposure apparatus,comprising the steps of detecting a surface position of a substrate tobe exposed while appropriately selecting an electrode to be used in eachelectrostatic sensor by the surface position detection apparatus of theexposure apparatus, and exposing the substrate while controlling theposition of the substrate to be exposed on the basis of a detectionresult.

[0053] According to this arrangement, even when the chip layout of printpattern of a wafer, i.e., the surface to be detected changes, anelectrode to be used in each electrostatic sensor is selected incorrespondence with the change. Distance measurement for surfaceposition detection is performed by making the electrode oppose apreferable measurement position or measurement area. Since the electrodeis simply selected by the selection means, the high-frequency voltage tobe applied is common to the electrodes appropriately selected in eachelectrostatic sensor and therefore is constant for the electrodes.Hence, accurate surface position detection is performed incorrespondence with a change in the surface to be detected.

[0054] According to a preferred aspect of the present invention, theelectrostatic sensor comprises a variable distance measurement positionelectrostatic sensor having, as the selection means, switching means forswitching the electrode to be used to change the measurement position orswitching means for switching the number of electrodes to be used tochange the measurement area.

[0055] The exposure apparatus is of a slit-scan type and comprises asurface position detection apparatus with the variable distancemeasurement position electrostatic sensor to detect tilt bypre-measurement for focus position control of the surface to be exposed,and means for controlling the switching means such that the measurementposition by two electrodes of each of two different electrostaticsensors of the surface position detection apparatus is set on anoutermost side within a scanning exposure width. Alternatively, theexposure apparatus comprises a surface position detection apparatushaving the variable distance measurement position electrostatic sensorto detect a position in a direction of an exposure optical axis bypre-measurement for focus position control of the surface to be exposed,and means for controlling the switching means such that the surfaceposition is not detected at a scribing line position.

[0056] The slit-scan exposure apparatus may comprise a surface positiondetection apparatus having the variable distance measurement positionelectrostatic sensor to detect the position in the direction of theexposure optical axis for pre-measurement for focus position control ofthe surface to be exposed. In this case, the exposure apparatuscomprises means for controlling the switching means such that large partof an exposure surface portion where high resolving performance isrequired is included in the measurement area.

[0057] The means for controlling the switching means can control on thebasis of the exposure layout. Under the control, even when the exposurewidth becomes small, electrodes are selected such that the electrodesfor calculating the tilt angle of the surface to be exposed are locatedwithin the width, thereby performing accurate focus position control. Inaddition, if a scribing line is located within the exposure slip, theelectrode can be switched to cope with a plurality of chip patterns. Inthe surface position detection apparatus having the variable distancemeasurement position electrostatic sensor, the detection area to beaveraged can be changed by switching the electrode to cope with aplurality of different chip layouts.

[0058] Further objects, features and advantages of the present inventionwill become apparent from the following detailed description of theembodiments of the present invention with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0059]FIG. 1 is a view showing a variable distance measurement positionelectrostatic sensor of a surface position detection apparatus accordingto the first embodiment of the present invention;

[0060]FIG. 2 is an explanatory view of the principle of the variabledistance measurement position electrostatic sensor shown in FIG. 1;

[0061]FIG. 3 is a view showing an application example of the variabledistance measurement position electrostatic sensor shown in FIG. 1 whenviewed from the direction of the exposure optical axis;

[0062]FIG. 4 is a view showing the application example of the variabledistance measurement position electrostatic sensor shown in FIG. 1 whenviewed from the scanning direction;

[0063]FIG. 5 is a view showing a specific application example of thevariable distance measurement position electrostatic sensor shown inFIG. 1;

[0064]FIG. 6 is a view showing another application example of thevariable distance measurement position electrostatic sensor shown inFIG. 1;

[0065]FIG. 7 is an explanatory view showing the detection area variableelectrostatic sensor of a surface position detection apparatus accordingto the second embodiment of the present invention;

[0066]FIG. 8 is an explanatory view of the principle of sensor shown inFIG. 7;

[0067]FIG. 9 is a schematic view showing a conventional surface positiondetection apparatus;

[0068]FIG. 10 is an explanatory view of the principle of distancemeasurement by the conventional electrostatic sensor;

[0069]FIG. 11 is a schematic view showing a surface position detectionapparatus using electrostatic sensors;

[0070]FIG. 12 is a view showing the layout of electrostatic sensors inthe conventional surface position detection apparatus;

[0071]FIG. 13 is a view for explaining a parameter calculation methodfor surface position control;

[0072]FIG. 14 is an explanatory view of the first problem of theconventional surface position detection apparatus that useselectrostatic sensors;

[0073]FIG. 15 is an explanatory view of the second problem of theconventional surface position detection apparatus that useselectrostatic sensors;

[0074]FIG. 16 is an explanatory view of the third problem of theconventional surface position detection apparatus that useselectrostatic sensors;

[0075]FIG. 17 is an explanatory view of the fourth problem of theconventional surface position detection apparatus that useselectrostatic sensors;

[0076]FIG. 18 is an explanatory view of the fourth problem of theconventional surface position detection apparatus that useselectrostatic sensors;

[0077]FIG. 19 is an explanatory view of the criterion for selecting asensor electrode of a tilt angle detection sensor formed from the sensorshown in FIG. 1;

[0078]FIG. 20 is an explanatory view of a problem posed when a memorycircuit is formed by exposure;

[0079]FIG. 21 is a flow chart showing a device manufacturing methodusing the exposure apparatus of the present invention; and

[0080]FIG. 22 is a flow chart showing details of the wafer process shownin FIG. 21.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0081] (First Embodiment)

[0082]FIG. 11 is a schematic view showing an exposure apparatus to whicha surface position detection apparatus according to the first embodimentof the present invention can be applied. Referring to FIG. 11, referencenumeral 1 denotes a reticle; 2, a reticle scanning stage (the scanningdirection is the X direction); 3, an illumination system for exposing awafer; 4, a reduction projecting lens; 5, a wafer; 6, a wafer chuck; 7,an X-Y stage; 8, a Z-tilt stage; and 20 and 20′, electrostatic sensorsconstructing part of the surface position detection apparatus. Theelectrostatic sensors 20 and 20′ cannot measure the surface position ofthe wafer 5 at the exposure position. So to pre-measure the surfaceposition of the wafer 5, when the wafer stage is to be scanned to theright (positive direction of the X axis), the sensor 20 is used, andwhen the wafer stage is to be scanned to the left (negative direction ofthe X axis), the sensor 20′ is used. A member 21 fixes the electrostaticsensors 20 and 20′ in position. To ground the electrostatic sensorsthrough their housing, the member 21 is made of a metal material such asaluminum and grounded. Reference numeral 22 denotes a control circuit;23, a detection signal (to ten-odd kHz) from the electrostatic sensor;and 24, a Z-tilt stage control signal. Each of the electrostatic sensors20 and 20′ comprises at least two sensors lined up in the Y direction soas to detect yawing (ωx) in scanning the wafer stage in the X direction.On the basis of the detection signal 23 from the electrostatic sensors20 and 20′, the control circuit 22 calculates a surface position Z andtilt component (tilt) of the wafer 5 and controls the Z-tilt stage 8,thereby accurately controlling the focus position.

[0083]FIG. 12 is a view showing a conventional layout of electrostaticsensors when viewed from the direction of the optical axis. Referencenumeral 25 denotes an exposure slit; and 27, a scanning direction. Inthis example, three sensors 201 to 203 are used as an electrostaticsensor (corresponding to the electrostatic sensor 20) to detect theheight and tilt of a wafer. Since the electrostatic sensors cannotdirectly measure the surface position at the exposure position,pre-measurement is performed by the sensors 201 to 203 mounted atpositions separated from the exposure slit 25 by a predetermineddistance in the scanning direction. Actually, since scanning isperformed in the negative direction of the X axis, similar sensors mustbe mounted as an electrostatic sensor (corresponding to theelectrostatic sensor 20′) in the negative direction, as described abovewith reference to FIG. 11, though they are not illustrated for thedescriptive convenience.

[0084]FIG. 13 is a view showing the arrangement in FIG. 12 when viewedfrom one scanning direction (positive side of the Y axis). Referencenumeral 26 denotes a surface (conductor) of an object (wafer) to bemeasured. The same reference numerals as in FIGS. 11 and 12 denote thesame parts in FIG. 13. Referring to FIG. 13, the sensor 202 is used todetect the height of the wafer, and the sensors 201 and 203 are used todetect its tilt. Let S1, S2, and S3 be the outputs from the sensors 201to 203, respectively. Then, the height Z [μm] and tilt ωx [rad.] aregiven by

Z=S2 [μm]

ωx=(S1-S3)/L[rad.]

[0085] (where L is the distance between the sensors 201 and 203)

[0086]FIG. 1 shows a variable distance measurement positionelectrostatic sensor used in the surface position detection apparatus ofthis embodiment, which is preferably stored in the exposure apparatusshown in FIG. 11. Reference numerals 301 to 306 denote sensorelectrodes. The section of each sensor electrode need not always becircular, as shown in FIG. 1. A change-over switch SW is used toarbitrarily select one of the sensor electrodes 301 to 306. Unselectedelectrodes are preferably grounded or may electrically float. Aconductive member 40 is called a guard ring and held at the samepotential as that applied to the selected sensor electrode. The guardring 40 prevents the current flowing through the sensor electrode fromflowing beyond the electrode area, thereby allowing accurate measurementof the distance between the electrode and the object (not shown) to bemeasured. The same reference numerals as in FIG. 10 denote the sameparts in FIG. 1. With this arrangement, the distance between the object(not shown) to be measured and an electrode selected by the switch SW ismeasured at the position of the electrode.

[0087] As a characteristic feature of the variable distance measurementposition electrostatic sensor according to the present invention, thedistance measurement position can be changed by arbitrarily selectingone of the plurality of sensor electrodes by the change-over switch SW.The surface position detection apparatus of the present invention has aplurality of sensor electrodes that can be switched, and the number ofsensor electrodes is not limited to six as in the above example. In thisexample, the sensor electrodes 301 to 306 are laid out in a line.However, the present invention is not limited to this layout, and anyarbitrary layout can be employed. As will be described later, when thisapparatus is used as the surface position detection apparatus of asemiconductor exposure apparatus, accurate focus control can beperformed because the electrode positions are fixed, unlike an apparatusin which a plurality of electrostatic sensors are switched by a circuit.Switching is preferably electronic switching instead of mechanicalswitching. The switching timing and sensor electrode selection methodwill be described later in detail together with application examples.

[0088]FIG. 2 is a view showing the principle of the variable distancemeasurement position electrostatic sensor shown in FIG. 1. Thechange-over switch SW arbitrarily selects one of the plurality of sensorelectrodes 301 to 306 arranged near an object 31 to be measured andconnects the electrode to an electrical circuit. Reference symbols d1 tod6 denote distances between the sensor electrodes 301 to 306 and theconductive substrate 31 at the electrode positions, respectively. Thedistances may be different from each other depending on the surfaceshape of the conductive substrate 31. The same reference numerals as inFIG. 10 or 1 denote the same parts in FIG. 2.

[0089] As shown in FIG. 2, a high-frequency voltage is applied from anoscillator OS to, e.g., the electrode 305 selected by the change-overswitch SW from the electrodes 301 to 306. An ammeter AM is connectedbetween the change-over switch SW and oscillator OS. The magnitude ofthe AC current flowing to the selected electrode 305 is measured by theammeter AM and a measurement device 32 connected to the ammeter AM. Thecurrent measurement result is input to an arithmetic circuit 33. Thedistance d5 between the selected electrode 305 and the object 31 to bemeasured is measured by arithmetic processing by the arithmetic circuit33.

[0090]FIG. 3 is a view for explaining an example in which the variabledistance measurement position electrostatic sensor shown in FIGS. 1 and2 is applied as the sensors 20 and 20′ for calculating the tilt angle ofa wafer in the exposure apparatus shown in FIG. 11. Variable distancemeasurement position electrostatic sensors 401 and 402 are used tocalculate the tilt angle. Reference numerals 301 to 308 denote sensorelectrodes. The sensor electrodes 301 to 304 construct the variabledistance measurement position electrostatic sensor 401, and the sensorelectrodes 305 to 308 construct the variable distance measurementposition electrostatic sensor 402. An exposure width 28 depends on thechip size formed on a wafer. Only a wafer portion positioned within thiswidth is exposed. Reference symbol L′ denotes the distance betweensensor electrodes used to calculate the tilt angle. The same referencenumerals as in FIG. 12 denote the same parts in FIG. 3. A measurementcircuit comprising the switch SW, ammeter AM, oscillator OS, andmeasurement device 32 is connected to each of the sensors 401 and 402,as in FIGS. 1 and 2. The outputs from the two measurement devices 32 aresupplied to the arithmetic circuit 33. The switch SW, ammeter AM,oscillator OS, and measurement device 32 may be shared by the sensors401 and 402.

[0091] With this arrangement, the sensor electrode for detecting thetilt angle can be switched to an arbitrary sensor electrode by theswitch SW to arbitrarily change the measurement position for tilt angledetection. As in FIGS. 12 and 13, the sensor 202 is used to detect theheight to the surface of the object to be measured.

[0092]FIG. 19 is an explanatory view of a sensor electrode selectionmethod. The variable distance measurement position electrostatic sensors401 and 402 are used to calculate the tilt angle of a wafer. The sensorelectrode 301 constructs the variable distance measurement positionelectrostatic sensor 401, and the sensor electrodes 305 and 307construct the variable distance measurement position electrostaticsensor 402. Reference numeral 26 denotes the surface of a wafer (objectto be measured). For the illustrative convenience, the sensor fordetecting the height and the remaining sensor electrodes are omitted.The same reference numerals as in FIG. 3 and the like denote the sameparts in FIG. 19.

[0093] As shown in FIG. 19, as the sensor electrode of one sensor 401for detecting the tilt angle, the sensor electrode 301 is used. As thesensor electrodes of the other sensor 402, the sensor electrodes 305 and307 are used. In this case, tilt angles are obtained as perωx″=(S1-S3″)/L″ and ωx′=(S1-S3′)/L′. When these tilt angles are comparedwith the actual tilt angle ωx, ωx≈ωx′, ωx<>ωx′. More specifically, whenan electrode separated from another sensor electrode by a largerdistance (in this case, the sensor electrode 307 because L′>L″) is used,the influence of the minute structure on the surface can be made smallerin calculating the tilt angle, so the tilt angle can be accuratelymeasured. That is, an outermost electrode within the exposure width isused as the sensor electrode for detecting the tilt angle.

[0094] In the example shown in FIG. 3, from the electrodes 303 to 306positioned within the exposure width 28, not the electrodes 304 and 305but the electrodes 303 and 306 that maximize the distance L′ between thesensor electrodes are selected. As a consequence, yawing of the objectto be measured can be accurately measured, and accurate focus controlcan be performed. Selection of sensor electrodes and actual processingof selecting the sensor electrodes by using the switch are automaticallydone according to a program stored in the surface position detectionapparatus. Since the user need not be aware of the algorithm or performoperation, cumbersome operation is unnecessary, and no errors occur.

[0095]FIG. 14 is a view for explaining a problem posed when not theapplication example described with reference to FIG. 3 but theconventional electrostatic sensor shown in FIG. 10 is used for thesurface position detection apparatus. The same reference numerals as inFIGS. 3 and 12 denote the same parts in FIG. 14. Referring to FIG. 14,the sensors 201 and 203 for detecting the tilt angle are positionedoutside the exposure area. A wafer having a step difference on itssurface because of the repeated process of forming layers has a largestep difference between the interior and exterior of the exposure area.For this reason, yawing of the wafer calculated on the basis of thedistance between the sensor electrode and the wafer surface, which isdetected outside the exposure area, and yawing of the surface within theexposure area, which need be actually measured, do not match.Accordingly, accurate focus control cannot be performed. However, asdescribed with reference to FIG. 3, when the electrostatic sensoraccording to the present invention is used as a tilt angle detectionsensor, the problem described with reference to FIG. 14 can be solved.

[0096]FIG. 4 is a view for explaining an application example shown inFIG. 3 that uses the variable distance measurement positionelectrostatic sensor of the present invention when viewed from thescanning direction. The same reference numerals as in FIG. 3 denote thesame parts in FIG. 4. As in FIG. 3, when the electrodes 303 and 306falling within the exposure width 28 are used to calculate the tiltangle, the actual tilt angle ωx′[rad.]=(S1′-S3′)/L′[rad.] can becalculated from the distances S′ and S3′ measured using theseelectrodes. Hence, accurate focus position control can be performed. Theheight Z−S2 to the object to be measured is detected using the electrode202, as in the prior art.

[0097]FIG. 15 is a view for explaining another problem posed when notthe application example described with reference to FIG. 4 but theconventional electrostatic sensor shown in FIG. 10 is used for thesurface position detection apparatus when viewed from the scanningdirection. The same reference numerals as in FIG. 12 or 14 denote thesame parts in FIG. 15. When the exposure width 28 is smaller than thedistance L between sensors, measurement is performed outside theexposure area. For this reason, the tilt angle ωx[rad.]=(S1- S3)/L[rad.] calculated from the values S1 and S3 detected by the sensors 201and 203 may largely differ from the actual tilt angle ωx′[rad.]. At thistime, accurate focus position control cannot be performed. However, asdescribed above with reference to FIG. 4, when the electrostatic sensoraccording to the present invention is used to detect the tilt angle, theproblem described with reference to FIG. 15 can be solved.

[0098]FIG. 5 is a view for explaining in detail an example ofmeasurement using the variable distance measurement positionelectrostatic sensor of the first embodiment shown in FIG. 1 as a sensorfor detecting the tilt angle. The same reference numerals as in FIG. 3denote the same parts in FIG. 5. When the tilt angle detection positionis switched to the sensor electrodes 304 and 305 positioned within theexposure width 28 using the switch (SW in FIGS. 1 and 2), the tilt angleof the wafer as an object to be measured can be accurately measured.Hence, accurate focus control can be performed. The height to the objectto be measured is detected using the electrode 202.

[0099]FIG. 16 is a view for explaining still another problem posed whennot the application example described with reference to FIG. 4 but theconventional electrostatic sensor shown in FIG. 10 is used for thesurface position detection apparatus. The same reference numerals as inFIG. 3 and the like denote the same parts in FIG. 16. As shown in FIG.16, when the exposure slit 25 is located near the outer peripheralportion of the wafer 5, a sensor used in the surface position detectionapparatus falls outside the range of the wafer, and the distance cannotbe accurately measured. For this reason, even when the chip size can beensured in the exposure area, the chip pattern cannot be printed byexposure, i.e., chips cannot be formed. However, as described withreference to FIG. 5, use of the electrostatic sensor according to thepresent invention as a tilt angle detection sensor eliminates theconventional problem described with reference to FIG. 16 wherein whenthe exposure slit is positioned near the outer peripheral portion of thewafer, and some sensors fall outside the wafer range, the distance tothe wafer cannot be measured, and exposure cannot be performed.

[0100] A method of selecting a sensor electrode to be used, i.e.,determining the distance measurement position when the variable distancemeasurement position electrostatic sensor is applied as a sensor forcalculating the tilt angle will be described next. As described withreference to FIG. 5, in the exposure process, the sensor electrode to beselected may change depending on the position of the exposure slit 25.When the exposure slit 25 is positioned near the outer peripheralportion of the wafer 5, a sensor electrode within the area of the wafermust be selected. On the other hand, when the exposure slit 25 is notnear the outer peripheral portion, an electrode position determined inadvance on the basis of the exposure width calculated immediately afterchip layout data is input before the start of exposure process isselected. That is, a sensor electrode that falls within the exposurewidth 28 and is located on the outermost side of the area of the waferis selected.

[0101]FIG. 6 is a view for explaining an example in which the variabledistance measurement position electrostatic sensor of this embodiment isapplied as a sensor for detecting the height in the surface positiondetection apparatus. A variable distance measurement positionelectrostatic sensor 403 is used to detect the height to the surface ofthe object to be measured. Reference numerals 311 and 312 denote sensorelectrodes of the variable distance measurement position electrostaticsensor 403. Reference numeral 29 denotes a scribing line (connectionportion) between adjacent chips, which is positioned under the sensorelectrode 311. The same reference numerals as in FIG. 3 or 12 denote thesame parts in FIG. 6.

[0102] In the arrangement shown in FIG. 6, when the sensor electrode tobe used in the height detection sensor 403 is switched to an arbitraryone of the sensor electrodes 311 and 312 using a switch (not shown), thesensor electrode (i.e., position of the sensor electrode to be used fordetection) for detecting the height to the surface of the object to bemeasured can be arbitrarily changed. As in FIG. 12 or 13, the sensors201 and 203 are used to detect the tilt angle. When the scribing line 29is positioned beneath the sensor electrode 311, as shown in FIG. 6, thesensor electrode is switched to the sensor electrode 312 positionedwithin the exposure width 28 using the switch (not shown) to detect theheight. With this arrangement, the distance to the surface of the objectto be measured can be accurately measured, and accurate focus controlcan be performed.

[0103] Selection of the sensor electrode and actual processing ofselecting the sensor electrode by using the switch are automaticallydone according to a program stored in the surface position detectionapparatus. Since the user need not be aware of the algorithm or performoperation, cumbersome operation is unnecessary, and no errors occur.Switching is performed on the basis of the chip layout data before thestart of exposure process. The reason for this is as follows. Since thechip layout (pattern) is common to one wafer and does not change duringexposure of the wafer, the sensor electrode used to detect the heightdoes not change during the exposure process. The sensor electrode to beused to detect the height is determined on the basis of the exposurewidth determined from the data.

[0104]FIG. 17 is a view for explaining still another problem posed whennot the application example described with reference to FIG. 6 but theconventional electrostatic sensor shown in FIG. 10 is used for thesurface position detection apparatus when viewed from the direction ofthe optical axis. FIG. 18 is a view for explaining this problem whenviewed from the scanning direction. The same reference numerals as inFIG. 6 or 14 denote the same parts in FIGS. 17 and 18. Referring toFIGS. 17 and 18, the scribing line 29 is present within the exposureslit 25. As shown in FIG. 18, even for a plurality of different chippatterns including this chip pattern, the scribing line 29 is positionedunderneath the electrostatic sensor 202 for detecting the height Z. Forthis reason, the distance, i.e., the height to the surface of the objectto be measured, which is to be actually detected, cannot be measured.Hence, accurate focus control cannot be performed. However, as describedabove with reference to FIG. 6, when the electrostatic sensor accordingto the present invention is used as the height detection sensor, theproblem described with reference to FIGS. 17 and 18 can be solved.

[0105] (Second Embodiment)

[0106]FIG. 7 is a view that best illustrates the characteristic featureof the detection area variable electrostatic sensor of a surfaceposition detection apparatus according to the second embodiment of thepresent invention. As shown in FIG. 7, in this sensor, a terminal 51 isconnected to one of terminals 52 and 53 by a switch SW. Referencenumeral 30 denotes a sensor electrode; and 30′, an electrode functioningas a sensor electrode only when the terminal 51 is connected to theterminal 52 by the switch SW. When the terminal 51 is connected to theterminal 53, only the electrode 30 functions as a sensor electrode, andthe electrode 30′ functions as a guard ring. The electrodes 30 and 30′have sections concentric with each other.

[0107] As shown in FIG. 7, a high-frequency voltage is applied from anoscillator OS to only the electrode 30 or both the electrodes 30 and 30′by the change-over switch SW. An ammeter AM is connected between thechange-over switch SW and oscillator OS. The magnitude of the AC currentflowing to only the electrode 30 or both the electrodes 30 and 30′ ismeasured by the ammeter AM and a measurement device 32 connected to theammeter AM. The current measurement result is input to an arithmeticcircuit 33. The distance d5 between the electrode 30 and a wafer as anobject to be measured is measured by arithmetic processing by thearithmetic circuit 33.

[0108] In the first embodiment, the detection position can be changed.In the second embodiment, the detection area (area of the sensorelectrode) can be changed. As described above, as one of thecharacteristic features of the electrostatic sensor, the detection areacan be almost uniformly averaged. In the arrangement shown in FIG. 7,since the detection area can be changed, the area to be averaged can bechanged.

[0109]FIG. 8 is an explanatory view of the principle of theelectrostatic sensor shown in FIG. 7, which allows to change the area ofthe sensor electrode, i.e., the detection area to be averaged. The samereference numerals as in FIG. 7 denote the same parts in FIG. 8. Asshown in FIG. 8, when the terminal 51 is connected to the terminal 52 byusing the switch SW to make the electrode 30′ function as a sensorelectrode, the area (S0 +S′) as the sum of an area S0 of the sensorelectrode 30 and an area S′ of the electrode 30′ can be set as thedetection area. Alternatively, by connecting the terminal 51 to theterminal 53 not to make the electrode 30′ function as a sensorelectrode, only the area (S0) of the sensor electrode 30 can be set asthe detection area of the electrostatic sensor.

[0110] According to the second embodiment, since the detection area canbe changed, the averaging area can be changed, and focus control can beeasily performed in accordance with the layout of chips to be formed byexposure.

[0111]FIG. 20 is a view for explaining that a conventional problem thatdefocus occurs depending on the chip layout can be solved by thisembodiment, when viewed from the scanning direction. Reference numeral41 denotes a surface of a memory cell; and 42, a surface of a peripheralcircuit. The same reference numerals as in FIG. 7 or 12 denote the sameparts in FIG. 20.

[0112] Defocus may occur when the height position is adjusted along thesurface of an object (resist) to be measured. This will be describedwith reference to FIG. 20. A device is roughly divided into the portionof the memory cell 41 and the portion of the peripheral circuit 42.Exposure areas where critical resolving performance is requiredgenerally concentrate at the portion of the memory cell 41. When onlythe sensor electrode 30 is used to detect a height position Z, a heightS2 to the surface of the peripheral circuit 42 is detected. In thiscase, defocus occurs on the surface of the memory cell 41 when theheight position shown in FIG. 11 is controlled on the basis of thedetected height position Z =S2.

[0113] To prevent this, not only the electrode 39 but also the electrode30′ is used as a sensor electrode using a switch (not shown in FIG. 20),as shown in FIGS. 7 and 8. At this time, a relation S2′<Z′<S2 holdsbetween a detected height position Z′, the height S2, and a heightposition S2′ to the surface of the memory cell 41. The specific value ofZ′ is determined by the area of the memory cell 41 opposing theelectrode 30′ and that of the peripheral circuit 42. When the area ofthe electrode 30′ is made sufficiently large to widen the detectionarea, the height position Z′, i.e., the focus position can be made closeto the height position S2′. Hence, the surface of the memory cell 41 canbe set within the focusing range, and the memory cell 41 and peripheralcircuit 42 can be properly exposed. <Embodiment of Device ManufacturingMethod>

[0114] Am embodiment of a device manufacturing method using theabove-described exposure apparatus will be described next. FIG. 21 showsthe flow of manufacturing a microdevice (e.g., a semiconductor chip suchas an IC or an LSI, a liquid crystal panel, a CCD, a thin-film magnetichead, or a micromachine). In step 1 (circuit design), the pattern of adevice is designed. In step 2 (mask preparation), a mask having thedesigned pattern is prepared. In step 3 (wafer manufacture), a wafer ismanufactured using a material such as silicon or glass. In step 4 (waferprocess) called a preprocess, an actual circuit is formed on the waferby lithography using the prepared mask and wafer. In step 5 (assembly)called a post-process, a semiconductor chip is formed from the waferprepared in step 4. This step includes processes such as assembly(dicing and bonding) and packaging (chip encapsulation). In step 6(inspection), inspections including operation check test and durabilitytest of the semiconductor device manufactured in step 5 are performed. Asemiconductor device is completed with these processes and delivered(step 7).

[0115]FIG. 22 shows the detailed flow of the wafer process (step 4). Instep 11 (oxidation), the surface of the wafer is oxidized. In step 12(CVD), an insulating film is formed on the wafer surface. In step 13(electrode formation), an electrode is formed on the wafer bydeposition. In step 14 (ion implantation), ions are implanted into thewafer. In step 15 (resist process), a resist is applied to the wafer. Instep 16 (exposure), the circuit pattern of the mask is printed on thewafer by exposure using the above-described exposure apparatus orexposure method. In step 17 (development), the exposed wafer isdeveloped. In step 18 (etching), portions other than the developedresist image are etched. In step 19 (resist peeling), the unnecessaryresist remaining after etching is removed. By repeating these steps, amultilayered structure of circuit patterns is formed on the wafer.

[0116] When the production method of this embodiment is used, a largedevice which is conventionally difficult to manufacture can bemanufactured at low cost.

[0117] As has been described above, according to the present invention,even when the state of the surface to be detected changes, the positionof the surface to be detected can be accurately detected incorrespondence with the change. According to the exposure apparatus towhich the present invention is applied, accurate focus control can beperformed. Hence, accurate device manufacture is allowed.

[0118] In addition, even when the size of the surface to be detectedchanges, the position of the surface to be detected can be detected byselecting a sensor electrode in correspondence with the change. Thisallows efficient exposure and efficient device manufacture.

[0119] The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention, the following claims are made.

What is claimed is:
 1. A position detection apparatus for detecting aposition of an object surface in a direction normal thereto, comprising:at least two detection sections; a selection section for selecting atleast one detection section from said at least two detection sections;and a measurement device for measuring the position of the objectsurface in the direction normal thereto using said detection sectionselected by said selection section.
 2. The apparatus according to claim1, wherein each of said at least two detection sections has anelectrode, and said measurement device applies an electrical signalcontaining an AC component to said electrode of the selected detectionsection to measure a distance between said electrode and the objectsurface.
 3. The apparatus according to claim 2, wherein said electrodesof said at least two detection sections oppose different portions of theobject surface.
 4. The apparatus according to claim 2, wherein saidelectrodes of said at least two detection sections are in one plane. 5.The apparatus according to claim 2, wherein said electrodes of said atleast two detection sections are concentric with each other.
 6. Theapparatus according to claim 2, wherein said selection sectionalternatively selects one detection section from said at least twodetection sections.
 7. The apparatus according to claim 2, wherein saidselection section selects at least one detection section such that thenumber of detection sections to be selected changes.
 8. The apparatusaccording to claim 1, wherein said selection section selects at leastone detection section in accordance with a shape of the object surface.9. The apparatus according to claim 1, wherein said apparatus comprisesat least two sets of said at least two detection sections, saidselection sections, and said measurement devices, and further comprisesan arithmetic section for calculating a tilt of the object surface onthe basis of a measurement result by said at least two measurementdevices.
 10. An exposure apparatus having a projecting lens forprojecting a pattern onto a substrate, a stage that moves whilesupporting the substrate, a position detection section for detecting aposition of a substrate surface in a direction of an optical axis, and acontrol section for controlling the stage on the basis of an output fromsaid position detection section, said position detection sectioncomprising at least two detection sections; a selection section forselecting at least one detection section from said at least twodetection sections; and a measurement device for measuring a position ofthe substrate in a direction normal thereto using said detection sectionselected by said selection section.
 11. The apparatus according to claim10, wherein each of said at least two detection sections has anelectrode, and said measurement device applies an electrical signalcontaining an AC component to said electrode of the selected detectionsection to measure a distance between said electrode and the substratesurface.
 12. The apparatus according to claim 11, wherein saidelectrodes of said at least two detection sections oppose differentportions of the substrate surface.
 13. The apparatus according to claim11, wherein said electrodes of said at least two detection sections arein one plane.
 14. The apparatus according to claim 11, wherein saidelectrodes of said at least two detection sections are concentric witheach other.
 15. The apparatus according to claim 10, wherein saidselection section alternatively selects one detection section from saidat least two detection sections.
 16. The apparatus according to claim10, wherein said selection section selects at least one detectionsection such that the number of detection sections to be selectedchanges.
 17. The apparatus according to claim 10, wherein said selectionsection selects at least one detection section in accordance with ashape of the substrate surface.
 18. The apparatus according to claim 10,wherein said selection section selects at least one detection section inaccordance with a position of the stage or the substrate.
 19. Theapparatus according to claim 10, wherein said selection section selectssaid detection section to be used for measurement so as not to measurethe position of the substrate in the direction normal thereto on ascribing line of the substrate.
 20. The apparatus according to claim 10,wherein said selection section determines the number of detectionsections for measurement in accordance with the pattern formed on thesubstrate.
 21. The apparatus according to claim 10, wherein saidselection section determines detection sections to be used formeasurement to reflect, on the measurement result, a position of anexposure area on the substrate in the direction normal thereto wherehigh resolving performance is required.
 22. The apparatus according toclaim 16, wherein said selection section determines the number ofdetection sections to be used for measurement to reflect, on themeasurement result, a position of an exposure area on the substrate inthe direction normal thereto where high resolving performance isrequired.
 23. An exposure apparatus having a projecting lens forprojecting a pattern onto a substrate, a stage which moves whilesupporting the substrate, first and second position detection sectionsfor detecting a position of a substrate surface in a direction of anoptical axis, and a control section for controlling a tilt of the stageon the basis of outputs from said first and second position detectionsections, each of said first and second position detection sectionscomprising at least two detection sections; a selection section forselecting at least one detection section from said at least twodetection sections; and a measurement device for measuring a position ofthe substrate in a direction normal thereto using said detection sectionselected by said selection section.
 24. The apparatus according to claim23, wherein each of said at least two detection sections has anelectrode, and said measurement device applies an electrical signalcontaining an AC component to said electrode of the selected detectionsection to measure a distance between said electrode and the substratesurface.
 25. The apparatus according to claim 24, wherein saidelectrodes of said at least two detection sections oppose differentportions of the substrate surface.
 26. The apparatus according to claim24, wherein said electrodes of said at least two detection sections arein one plane.
 27. The apparatus according to claim 23, wherein saidselection section alternatively selects one detection section from saidat least two detection sections.
 28. The apparatus according to claim23, wherein each of said selection section of said first positiondetection section and said selection section of said second positiondetection section selects a detection section such that both saiddetection section of said first position detection section and saiddetection section of said second position detection section, which areto be used for measurement, are positioned on an inner area of a widthof the pattern projected by the projecting lens and a distance betweensaid detection sections is maximized.
 29. The apparatus according toclaim 28, wherein the substrate is exposed while projecting slit-shapedlight onto the substrate through the projecting lens and moving thestage.
 30. The apparatus according to claim 23, wherein each of saidselection section of said first position detection section and saidselection section of said second position detection section selects adetection section such that both said detection section of said firstposition detection section and said detection section of said secondposition detection section, which are to be used for measurement, arepositioned inside a width of the pattern projected by the projectinglens on the substrate and a distance between said detection sections ismaximized.
 31. The apparatus according to claim 30, wherein thesubstrate is exposed while projecting slit-shaped light onto thesubstrate through the projecting lens and moving the stage.
 32. Aposition detection method of detecting a position of an object surfacein a direction normal thereto, comprising: the selection step ofselecting at least one detection section from at least two detectionsections; and the measurement step of measuring the position of theobject surface in the direction normal thereto using the selecteddetection section.
 33. A method of controlling an exposure apparatushaving a projecting lens for projecting a pattern onto a substrate, astage which moves while supporting the substrate, a position detectionsection for detecting a position of a substrate surface in a directionof an optical axis, and a control section for controlling the stage onthe basis of an output from said position detection section, comprising:the selection step of selecting at least one detection section from atleast two detection sections; and the measurement step of measuring aposition of the substrate in a direction normal thereto using theselected detection section.
 34. A method of controlling an exposureapparatus having a projecting lens for projecting a pattern onto asubstrate, a stage which moves while supporting the substrate, first andsecond position detection sections for detecting a position of asubstrate surface in a direction of an optical axis, and a controlsection for controlling a tilt of the stage, each of said first andsecond position detection sections comprising at least two detectionsections, comprising: the selection step of selecting at least onedetection section from said at least two detection sections of saidfirst position detection section and at least one detection section fromsaid at least two detection sections of said second position detectionsection; and the measurement step of measuring the tilt of the substrateusing the selected detection section of said first position detectionsection and the selected detection section of said second positiondetection section.
 35. A device manufacturing method comprising thesteps of: placing a substrate applied with a resist film on a stage ofan exposure apparatus; selecting at least one detection section of atleast two detection sections for measuring a position of the substratein a direction of an optical axis and measuring the position of thesubstrate on the stage in the direction of the optical axis using theselected detection section; controlling the stage in accordance with ameasurement result in the measurement step; forming a pattern on thesubstrate on the stage by exposure; and developing the substrate.
 36. Adevice manufacturing method comprising the steps of: placing a substrateapplied with a resist film on a stage of an exposure apparatus;selecting at least one detection section from each of two positiondetection sections each having at least two detection sections formeasuring a position of the substrate in a direction of an optical axisand measuring a tilt of the substrate on the stage using the selecteddetection sections; controlling the tilt of the stage in accordance witha measurement result in the measurement step; forming a pattern on thesubstrate on the stage by exposure; and developing the substrate.